Control of large-scale wettability using micro-amounts of selective solvents

A simple approach was used to control the large-scale wettability of polymer-coated surfaces merely by adding micro-amounts of selective solvents of different polarity to tri-block copolymer solutions. An amphiphilic tri-block copolymer, poly(ethylene oxide)-poly(dimethylsiloxane)-poly(ethylene oxide)(PEO-PDMS-PEO), was used to form micelles and reverse micelles by adding micro-amounts of a selective solvent to the initial solution. The micellar and reverse micellar film coatings show different wettability from hydrophilic to hydrophobic, and even from superhydrophilic to superhydrophobic when micro-scale roughness is involved. The structures of the micelles and reverse micelles were studied by transmission electron microscopy and ato-mic force microscopy, and the surface chemical composition of the film coatings was determined by X-ray photoelectron spectroscopy(XPS). The results reveal that the main cause of differences in wettability is the diffe-rent surface chemical compositions induced by the different structures of micelles and reverse micelles.